[From folk singer Tom Morgan's "The John T. Scopes Trial (The Old Religion's Better After All)".]

You may find a new belief

It will only bring you grief

For a house that's built on sand is sure to fall.

Argued that evolution was a "new belief", and "that the old religion's better after all". But equally (and possibly more) plausible to argue that religion is built on sand — the famously unreliable nature of recorded history and superstitious beliefs — rather than scientific evidence that can be tested repeatedly by anyone, anytime.

Robin Williams: First of all, it seems, like, a little redundant for him to take Viagra you know? [silence] The fact that he takes it, he gets taller. You know, it's a wonderful— [finally some laughter] I mean, why, what do you need, right… it's a hard thing, when he's a big prick already—

[Now, laughs and applause.]

Leno: Ho!

Note that the first punch line ("a little redundant") was completely missed by all, the second ("he gets taller") only fitfully appreciated, and the third required an explicit use of the phrase "big prick" for most people to get the joke. No wonder MST3K went over the heads of so many people.